The present invention relates to an image processing device which changes the colors of an image to be displayed on a CRT screen.
A color change technique is one of the image processing techniques. The generation of an image which has an appearance that is different from an original image has been made by converting the color data of the area corresponding to the area whose color will be changed. For example, when the color of a green leaf is changed, only the area corresponding to the leaf is turned into yellow. This processing can be made by replacing the R(RED), G(GREEN), and B(BLUE) data of each of the pixels which compose an image with different data, respectively. Rewriting the data of each pixel in the image, however, increases the number of accesses by hardware, such as CPU, to an image memory. This leads to an increase of the image processing period of time. Accordingly, such a system is required to have a function for responding to transferred information at a high speed or have high resolution or very large storage capacity of an image memory and is unsuitable for frequent color change processings. Therefore, a hardware provision of a special construction is necessitated, such as a processor specialized for image processing. This causes hardware systems to be complicated and requires a special program to be created.
Further, such image processing for a color change results from replacing data stored in an image memory and causes the data to be erased after the replacement is completed. Therefore, an image processing method is unsuitable for systems such as those for the simulation of a color change in which an original color of an image is frequently compared with the color that has been changed from the original color.